Smule: the social music app that lets fans sing karaoke with Jessie J

Apps that let fans create their own versions of their favourite songs - and duet with the likes of Jessie J - have put the US company on the music map

Jessie J has performed with a host of musicians in her time: Dizzee Rascal, Ariana Grande, 2 Chainz, Queen, David Guetta, Mary J. Blige, Tom Bleasby" Wait, Tom who?

Bleasby is the fan whose video duet with Jessie J went viral last month, notching up nearly 3.6m views on his own YouTube channel and another 10.3m on Facebook after the star shared it with her followers.